Evolutionary and ecological studies on the circum-north Pacific elements, the super-family cottoid

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To verify the polyphyletic evolution hypothesis of copulating within cottoid, we had the researches to collection of fish samples for investigation of molecular phylogeny including the western Pacific species and the fine structural morphology of the reproductive tract on cottoid species. We collected 5 families 60 species 1500 specimens during three expeditions, the Puget sounds and Vancuver in March 2006, Unalaska island in July 2006, and Peter the Great Bay in November 2007.Process of gonadal sex differentiation and formation of reproductive organ were investigated in uncopulative sculpin Cottus. In Cottus, the differences in morphology of urogenital projection between male and female appeared considerably late period after having completed gonadal sex differentiation.Remarkable specialization was admitted in the morphology of testis and sperm among Cottidae. Especially, some common characteristics (slender sperm head, eosin positive-secretion, sperm bunch, asynchronous spermatogenesis) were observed overcoming genus in copulative sculpins. It is thought that each characteristic is an adaptation to the copulation related to the spermatogenesis and the sperm motility.We investigated the differentiation of germ cells toward normal fertile sperm (eusperm) and non-fertile dimorphic sperm (parasperm) by using Hemilepidotus gilberti. We obtained eusperm and parasperm by cell culture of germ cells from spermatocytes collected from teites, indicating DNA-duplicating spermatocytes are potent to autonomously progress a part of spermatogenesis to form parasperm. By electrophoretic analysis of acid extracts from eusperm and parasperm, specific protein bands for each type were detected in its electrophoretic patterns, indicating the condensation of nucleus of the different type of sperm occur through a different sperm-specific nuclear basic proteins.